170 



and Declination, or, in other words, make a map of the stars 

 observed. Owing to inconvenience in attaching such an 

 apparatus to our instrument, the plan was not put in execu- 

 tion. 



We will now proceed to give a description of the Chart- 

 ing Machine. Fig. 1 is a perspective of the machine, as 

 seen from the southeast. 



This apparatus is firmly fastened to the south side of the 

 west pier. It is connected with the clamp arm of the Tele- 

 scope by means of the horizontal rod {f), 40 in. in length. 



A clock work mechanism, having a half second's pendu- 

 lum (p), carries the cylinder (a), 6 in. in length and 10 in. 

 in diameter ; which revolves from west to east, and makes 

 a complete revolution every hour. 



Directly over the cylinder is mounted, on a horizontal 

 axis, the compound lever (6, /) ; to the lower end of which, 

 by means of a short horizontal^arm and joint, a pencil is 

 held in a vertical position over the axis. The lower part of 

 this lever (6), is 18 in. long ; the upper part (/) is 6 in. long. 

 In order to magnify as much as possible the angular motion 

 of the clamp arm, we attach to it a strong iron bar, 25 in. in 



Fig. 2. 



length. At the lower end of this bar is a cross piece, fig. 

 2, 6 in. long, holding a number of cylindrical pins (p). 

 Each of these pins has a notch cut in the middle, of the 



